1. Field of the Invention
The present invention relates to a tensioning element, a chain conveyor and a means for opening and closing the tensioning element.
When conveying packaging film webs on packaging machines, it is necessary to pull the packaging film webs taut while simultaneously conveying them, wherein the packaging film web is clamped at the start of the machine and released again at the end of the packaging machine. The constantly alternating tensioning and releasing of the packaging film web requires a mechanism with which these procedures may be performed using simple means and with a high degree of reliability. According to the prior art, chains have proven effective for this purpose, each link being provided with a corresponding tensioning element, which is opened and closed again on passing over a first chain wheel, so clamping the packaging film web. On passing over a second chain wheel, the tensioning element is opened again and then closed, wherein in this case the packaging film web is released again.
2. Brief Description of Related Developments
The tensioning elements used therefor are disclosed in DE 195 25 523, DE 33 15 419, DE 23 55 921 and in FR 81 110 60. The tensioning elements according to the prior art have the disadvantage, however, of being comparatively complex to produce and/or of wearing comparatively quickly.
The object of the present invention was therefore to provide a tensioning element which does not exhibit the disadvantages of the prior art.